It is not often that you see an actor get right to the heart of a character in a solo performance but this is indeed the case with Carey Mulligan, who brings a luminous quality as well as an ability to seem quiet and purposeful to the role of an unnamed woman in Dennis Kelly’s 90-minute monologue, Girls and Boys (Royal Court’s Jerwood theatre downstairs).

The play tells the story of two people who fall in love with each other after an encounter in an airport queue. “I met my husband in the queue to board an easyjet flight and I have to say I took an instant dislike to the man”. There’s Romance and passion, then domesticity and procreation. Before long they begin to settle down, buy a house, juggle careers (she finds success in TV documentaries, he less so, in antique wardrobe sales) and have kids. But their world starts to unravel and normal family life takes a disturbing turn.

Kelly touches on loss, the self-absorption of family life and the ways in which parents’ playfulness can condition boys and girls to follow certain narrow paths. But the story lacks substance and the character of the husband is sketchily drawn, while the piece occasionally feels manipulative. We are only hearing one side of the disintegration of a relationship.

No such doubts, however, surround Mulligan’s performance. As the story unfolds, she brings the skill of a born raconteur to the piece, getting us to hang on to every word. She displays spot on comic timing to the more entertaining passages, every articulate hand gesture and wry arch of her eyebrows contributing. But there’s something in her eyes, some sadness behind the smiles that make you realize this is not going to be a fairytale romance fulfilled. Barefoot, in tailored plum trousers and mustard silk shirt and with a south London accent, she succeeds in taking us to the darkest recesses of human behavior without a trace of sensationalism. Mulligan is, I should add, equally adept at re-enacting domestic life, complete with two wayward (and invisible) children. She presents us with a fully rounded character; a woman surprised by her own success, gratified by her own ambition and determined not to be destroyed by tragedy.

Es Devlin provides a chic, elegant living room set with its fleetingly seen sky blue colour magically bleaching out, appearing at intervals and giving the piece a realist, rather than static, feel.

This, then, is a flawed, unsettling work, given a real kiss of life by Mulligan’s astonishing performance.